SLASF21 December   2022 AFE78101 , AFE88101

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Timing Requirements
    7. 6.7  Timing Diagrams
    8. 6.8  Typical Characteristics: VOUT DAC
    9. 6.9  Typical Characteristics: ADC
    10. 6.10 Typical Characteristics: Reference
    11. 6.11 Typical Characteristics: Power Supply
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Digital-to-Analog Converter (DAC) Overview
        1. 7.3.1.1 DAC Resistor String
        2. 7.3.1.2 DAC Buffer Amplifier
        3. 7.3.1.3 DAC Transfer Function
        4. 7.3.1.4 DAC Gain and Offset Calibration
        5. 7.3.1.5 Programmable Slew Rate
        6. 7.3.1.6 DAC Register Structure and CLEAR State
      2. 7.3.2 Analog-to-Digital Converter (ADC) Overview
        1. 7.3.2.1 ADC Operation
        2. 7.3.2.2 ADC Custom Channel Sequencer
        3. 7.3.2.3 ADC Synchronization
        4. 7.3.2.4 ADC Offset Calibration
        5. 7.3.2.5 External Monitoring Inputs
        6. 7.3.2.6 Temperature Sensor
        7. 7.3.2.7 Self-Diagnostic Multiplexer
        8. 7.3.2.8 ADC Bypass
      3. 7.3.3 Programmable Out-of-Range Alarms
        1. 7.3.3.1 Alarm Action Configuration Register
        2. 7.3.3.2 Alarm Voltage Generator
        3. 7.3.3.3 Temperature Sensor Alarm Function
        4. 7.3.3.4 Internal Reference Alarm Function
        5. 7.3.3.5 ADC Alarm Function
        6. 7.3.3.6 Fault Detection
      4. 7.3.4 IRQ
      5. 7.3.5 Internal Reference
      6. 7.3.6 Integrated Precision Oscillator
      7. 7.3.7 One-Time Programmable (OTP) Memory
    4. 7.4 Device Functional Modes
      1. 7.4.1 DAC Power-Down Mode
      2. 7.4.2 Reset
    5. 7.5 Programming
      1. 7.5.1 Communication Setup
        1. 7.5.1.1 SPI Mode
        2. 7.5.1.2 UART Mode
      2. 7.5.2 Serial Peripheral Interface (SPI)
        1. 7.5.2.1 SPI Frame Definition
        2. 7.5.2.2 SPI Read and Write
        3. 7.5.2.3 Frame Error Checking
        4. 7.5.2.4 Synchronization
      3. 7.5.3 UART
        1. 7.5.3.1 UART Break Mode (UBM)
      4. 7.5.4 Status Bits
      5. 7.5.5 Watchdog Timer
    6. 7.6 Register Maps
      1. 7.6.1 AFEx8101 Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Multichannel Configuration
    2. 8.2 Typical Application
      1. 8.2.1 4-mA to 20-mA Current Transmitter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Start-Up Circuit
          2. 8.2.1.2.2 Current Loop Control
          3. 8.2.1.2.3 Input Protection and Rectification
          4. 8.2.1.2.4 System Current Budget
        3. 8.2.1.3 Application Curves
    3. 8.3 Initialization Set Up
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.2.5 External Monitoring Inputs

The AFEx8101 have two analog inputs for external voltage sensing. Channels 1 and 2 for the CCS pointer are for external monitoring inputs that can be measured by pins AIN0 and AIN1, respectively. The input range for the analog inputs is configurable to either 0 V to 1.25 V or 0 V to 2.5 V. The analog inputs conversion values are stored in straight binary format in the ADC registers. The ADC resolution can be computed by Equation 7:

Equation 7. 1   L S B = V R A N G E 2 12

where

  • VRANGE = 2.5 V for the 0‑V to 2.5‑V input range or 1.25 V for the 0‑V to 1.25‑V input range.

Figure 7-10 and Table 7-6 detail the transfer characteristics.

GUID-F4A7E482-3409-4FA8-A987-48B8C0245116-low.gif Figure 7-10 ADC Transfer Characteristics
Table 7-6 Transfer Characteristics
INPUT VOLTAGE CODE DESCRIPTION IDEAL OUTPUT CODE
≤1 LSB NFSC Negative full-scale code 000
1 LSB to 2 LSB NFSC + 1 Negative full-scale code plus 1 001
(VRANGE / 2) to (VRANGE / 2) + 1 LSB MC Midcode 800
(VRANGE / 2) + 1 LSB to (VRANGE / 2) + 2 LSB MC + 1 Midcode plus 1 801
≥ VRANGE – 1 LSB PFSC Positive full-scale code FFF

For these external monitoring inputs, the ADC is configurable for both data rate and voltage range. The data rate is set to either 640 Hz, 1280 Hz, 2560 Hz, or 3840 Hz with the ADC_CFG.CONV_RATE bits. The range of the ADC measurement is set with the ADC_CFG.AIN_RANGE bit. The ADC range is 2 × VREF when the bit = 0; the ADC range is VREF when the bit = 1. ADC_CFG.AIN_RANGE only controls the range if PVDD >  2.7 V. When PVDD = 1.8 V, the range is VREF regardless of the setting.

When the ADC conversion is completed for AIN0 and AIN1, the resulting ADC data are stored in the ADC_AIN0.DATA and ADC_AIN1.DATA bits at 24h and 25h of the register map.

If the external monitoring inputs are not used, connect the AIN0 and AIN1 pins to GND through a 1-kΩ resistor.